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TIMESTAMPS

Low Earth Orbiting Satellites and Internet-Based Messaging
Services

Abstract

In the rush to embrace ever-greater capacities supporting resource-demanding
systems such as the World Wide Web, the utility of "real-enough-time"
services based on low bandwidth store-and-forward messaging tends
to be overlooked. Low-end wireless technologies, including small
communications satellites in low earth orbit (LEO) with concomitant
low-cost ground-based hardware, can make dramatic impacts in isolated
and rural areas, especially in the developing countries of Asia,
Africa and Latin America. Such areas are currently left out of
the "Internet revolution" as rural teledensity targets
(telephones per hundred residents) are not met. These regions
may be even further negatively impacted by the trend towards privatization
in telecommunications that may view investment in rural infrastructure
and connectivity as uneconomic.

Development activities in rural areas are frequently characterized
by critical, time-dependent information needs. The time value
of information is obvious in rehabilitation and relief response
to disasters. Not usually reported, timeliness is also urgent
in many standard projects. If real-enough-time access can reduce
turnaround query-response cycles from weeks and months to hours
or a day or two, this will usually be sufficient.

Volunteers in Technical Assistance (VITA) has been a leader in
the use of LEO satellites to provide real-enough-time services.
Such satellites in polar orbits pass over all points on earth
several times daily, permitting automatic uploading, downloading
and delivery when combined with Internet gateway services. A brief
history of the first efforts is provided as well as a description
of the current attempt to develop high-quality messaging and data
services in partnership with Final Analysis Inc., an innovative
satellite and network services firm.

Technical descriptions, including operational parameters and use
of the Internet as transport for both services, are provided.

The paper concludes that known constraints to widespread adoption
of LEO and other wireless technologies enhancing significant impacts
in rural development are less technical or human resource-limited
than regulatory and bureaucratic in nature.

Introduction

An answer to a technical problem that takes minutes to obtain
in Europe can take months to obtain in Somalia or Sudan. To give
just one example, a medical advisor in Mogadishu needed background
information on excretion of anti-malarials in breast milk to help
him decide on the details of a prophylaxis programme for about
half a million people. The agency funding him had no staff in
Europe who were themselves qualified to make a thorough search
for this information or who knew who to ask to do it for them.
The telephone calls necessary to set up and pay for a search through
a Western information centre would have taken weeks, given the
communication problems at that time. The solution was to get a
friend who was passing through Nairobi to pay himself for a search
in Europe, personally photocopy the papers concerned, and then
to mail the printout and copies of papers to Mogadishu. The total
time needed to get the information on this routine enquiry was
about four weeks. The programme was already underway when the
material arrived. Hundreds of highly technical decisions affecting
huge numbers of people are made every month in relief programs
with a bare minimum of scientific background data (1).

This is another way of saying that the accuracy of information
is an important but insufficient condition for effective use in
developing countries. In order for most technical and logistical
information to be used in the execution of a project (or in this
case, a relief operation) it must be timely as well. Scientists,
engineers and physicians--frequently sources of crucial data--are
usually aware of the time dimension of technical information requirements
in their own professional activities; however, they might not
always appreciate that good timing is also highly operative in
many relief and development projects alike.

This is not to say that every project always needs information
within a few hours or even a few days. Indeed, many do not, but
such projects also tend to be based out of urban centers with
relatively easy howbeit costly access to the limited national
infrastructure. A refugee camp, an agricultural project in a remote
valley, a scientist monitoring the spread of AIDS or the movement
of locusts through remote sections of Africa all require the ability
to transmit and receive technical data and information reliably
when the situation demands. These applications require that the
communications link be reliably available on short notice without
it having to be re-established each time from scratch.

While the paragraph quoted above was written a decade ago, it
remains true today, not in the least diminished by progress in
digitally-switched-telephone line-mediated Internet connectivity
throughout the developing world and indeed in some of urban Africa.
One only has to consider what has happened to Somalia in the interim
to realize that sole dependency on the terrestrial wire-based
communications infrastructure has serious limitations. While especially
true for Africa (2), most rural and isolated regions worldwide
outside of North America and western Europe are almost completely
without connectivity of any kind, including e-mail.

Given the emphasis on expanding bandwidth capacities to accommodate
real-time resource gluttons (e.g. World Wide Web), the utility
of real-enough-time services based on store-and-forward messaging
tends to be overlooked, as has the possibility of providing such
services through low-end wireless technologies, including small
communications satellites in low-earth orbit with corresponding
low-cost ground-based hardware.

The problem

Isolated and rural areas of many developing countries in Asia,
Africa and Latin America have been and continue to be effectively
shut out of the Internet revolution. Two-thirds of people living
in the poorer countries have no access to any form of telecommunication
and 49 of the world's poorest countries are characterized with
teledensities of less than one (0.72) telephone per hundred residents
(3). While the International Telecommunications Union predicts
average growth in 54 of the poorest countries to 2.17 telephones
per hundred residents by the year 2000, the Maitland Commission's
1984 estimate of one telephone per hundred residents by 1988 was
dramatically wrong (only 0.72 by 1994). While some of this represents
urban back-log that will hopefully be reduced with the advent
of newly capitalized digital switch technology, rural areas will
still suffer, possibly because of the additional burden of the
trend toward privatization. Given sparse populations and dispersed
markets in rural areas, there is usually no profit-borne incentive
to improve and expand service in these regions by urban-oriented
enterprises. Another by-product of privatization, at least in
some Latin American and African countries, is that Internet services
tend to be provided through the newly privatized companies in
a monopolistic fashion. In Belize, for example, even third-party
re-sellers of local and international telephone circuits for commercial
electronic mail are not permitted as of late 1995 (4).

Such environments do not instill confidence that priority will
ever be given to most rural and isolated areas using normative
infrastructural standards and policies/priorities. Yet information
needs for relief and development are frequently critical, as illustrated
in the opening passage above.

Aside from the obvious time-critical nature of disaster and relief
situations, information that is crucial to project execution is
also time dependent. The same information, if delivered after
a certain time, has lost much--if not all--of its value. This
is frequently due to the intrinsic value of the information itself,
e.g., preparation of proposals and budgets or technical assistance
needed at a highly-specific point in time. Even more important
is the potential loss of human and material resources that may
be used in other projects or wasted altogether if not used when
critically needed.

From the standpoint of planners, projects are sometimes viewed
as objectives compartmentalized into specific activities, all
having discrete beginning and ending points. From the perspectives
of field staff, however, it is often more realistic to consider
accomplished objectives as having successfully recognized and
exploited windows of opportunity. When the window is open, it
is critical to have the right information available at that time.
When the window is closed, (e.g., field staff have promised skeptical
village leaders information on a new treatment for cholera but
have not delivered same) it may be twice as difficult if not impossible
to reactivate interest. Village leaders, usually characterized
with multiple and even extreme demands constantly made on their
time, move on to other projects. On the other hand, when information-communication
channels are reliable, interesting and unexpected things can happen.
A VITA-supported groundstation in Tanzania operating on a LEO
satellite (UoSat-3, see below) is currently using VITA's existing
Internet gateway to order parts and derive technical assistance
for the construction of two small aircraft, built from kits (5).
One is already flying and serving health and other needs in remote
regions of that country. This use could not have been predicted
when the groundstation was first established.

Most useful technical information is the result of multiple pairs
of query-response; each response provides more feedback for an
ever-refined query. This makes the reduction in turn-around time
important and suggests that communication modes that specifically
address reliability and speed, particularly from isolated areas,
are enormously significant for a great variety of rural projects
and activities. Indeed, any conceivable development application
will benefit from the availability of this capability. Instant
access is usually not required, but if the turn-around is measured
in hours (or a couple of days) as opposed to weeks or months,
the impact on efficiency and useful function can be dramatic.
When one considers that 13,000 international nonprofit organizations
plus a plethora of bilateral (USAID and aid-granting foundations
from North American, Canadian and European countries) and multilateral
agencies (the World Bank, UNDP, WHO, WMO, UNHCR, etc.) are all
involved in supporting rural development in some form, a flexible
set of technological options permitting "real-enough time"
with complementary rural communication policies could have sizeable
impacts in these days of diminishing budgets.

Even within communities of experienced Internet users, a curious
phenomenon exists. At the very moment when resource demands on
bandwidth and computer power are exploding for ever-more sophisticated
real-time applications ("Internet telephone" being only
a recent example), the capability of accessing much of this same
information via e-mail is also increasing. The most comprehensive
single source of information on this, "Doctor Bob's Guide
to Offline Internet Access," contains nearly 30 pages of
resource listings and explanations in the most recent edition
(6). Included are references to ftp by e-mail, Archie by e-mail,
Gopher by e-mail, Veronica by e-mail, Usenet by e-mail, Usenet
searches, WAIS searches, World Wide Web by e-mail, World Wide
Web searches by e-mail, e-mail-based mailing lists and "directory
assistance." Many other "e-mail extras" exist as
well, such as e-mail-to-fax services, dictionary lookups, virus
protection software, and even "e-mail-to-snailmail"
courier services!

A solution: From "IP-ignorant" to "IP-aware"
LEO satellite-based messaging systems

The early advent of LEO satellites for relief and development
was championed by VITA (which in 1992 received a "pioneer's
preference" toward a nonexperimental permanent license by
the Federal Communications Commission [FCC] in the United States).
Working with the University of Surrey (Guildford, England), Surrey
Satellite Technology, Ltd., the international amateur radio community
and its own volunteers, VITA was able to show that communication
with LEO satellites (UoSat-2, launched in 1984, and UoSat-3 in
1990) is a technically practical option for developing countries.
Modified amateur radio hardware for groundstations was used with
specially-developed communications software (based on an X.25-derived
protocol), with additional software to control tracking antenna
systems operating in the background. Both satellites were launched
in polar orbits at altitudes of roughly 800 km, providing for
four passes per day at the equator and increasing to fourteen
as one approaches the polar latitudes, and at this writing both
are still functional. Passes vary in length between roughly 5
and 15 minutes with maximum elevations also changing (but all
predicted by the tracking software, which is updated on a monthly
basis through the transmission of Keplerian orbital elements from
NASA). With UoSat-3 and improved datagram-like protocols, good
passes permit the transfer of several hundred thousand bytes of
information per pass at the nominal transmission rate of 9600
bps to and from groundstations.

VITA installed or assisted in the installation of more than 25
such ground stations, most in Africa (7), for use on UoSat-3 as
well as assisting in the design and financing of the PACSAT Communications
Experiment satellite payload. VITA also demonstrated, through
a village utility project on several Indonesian islands, that
LEO technology could be used reliably in an unattended mode for
the transfer of telemetry data (8). SatelLife, a Boston-based
organization, has contributed significantly to the experiential
knowledge base of using LEO satellites for delivery of health
and medical information (9).

This early experimentation and demonstration occurred mostly before
the explosion of interest in the Internet registered in the past
few years. Installed groundstations communicated directly with
other groundstations with transfer of messages destined for other
networks via "sneakermail." With the increasingly widespread
standardization and availability of IP addressing to public and
private e-mail systems alike, VITA devised an innovative means
to translate groundstation addresses into their Internet equivalents,
e.g., groundstation addressing such as "v.kib" (a VITA-supported
station in Kibidula, Tanzania) becomes "v+kib@sat.vitanet.org."
A gateway connection between the "vitanet.org" machine
and the VITA/Arlington satellite station (physically located within
the same office in Virginia, USA) was established by providing
the satellite station with a Fidonet "point" address
(i.e., 1:109/165.1) which polls the "boss" machine (1:109/165)
before and after passes. The packing and exchange of messages
occurs using standard Fidonet mailer software. The "boss"
machine, also known as "vitanet.org," is equipped with
translation software for standard UUCP polling to a local Internet
service provider. Sub-domains, such as "sat." in the
above address, are assigned by the VITA system operator. Thus,
gateway function is fully automatic in both directions, permits
unattended operation, uses low cost or public domain Fidonet mailers,
is adapted and maintained with in-house expertise, but is not
RFC-822 compatible.

In 1992, VITA participated with others (specifically the private
companies OrbComm and Starsys interested in the "little LEO"
spectrum [frequencies below 1 GHz] for asset tracking and meter
reading applications) in the ITU's World Administrative Radio
Conference, a regular mega-meeting of this U.N.-affiliated organization
that allocates radio spectrum and usage worldwide. The purpose
was to persuade the 164 ITU members to allocate slots in very
high frequency (VHF) bands and ultra high frequency (UHF) bands
for "little LEO" services. The successful result was
an allocation for "Non-Voice, Non-Geostationary Mobile Satellite
Services," which in turn was created by the FCC and in which
VITA and the other "little LEO" applicants were eventually
awarded U.S. licenses (after an extensive "negotiated rulemaking"
process among the parties imposed by the FCC).

VITA entered into a joint venture with a U.S.-based satellite
construction and launch company, CTA, to build and launch a commercial-grade
satellite in exchange for access to VITA's license over the United
States. This satellite was launched on 15 August 1995 from Vandenberg
Air Force Base but unfortunately failed to reach orbit after a
malfunction in the Lockheed-Martin rocket and its subsequent destruction
by ground crew (10).

VITA now has a new arrangement with another U.S.-based company,
Final Analysis, an innovative aerospace engineering and telecommunications
firm providing turnkey systems from ground systems and operations,
to satellite bus development and payload design and launch services.
The satellite containing the VITA communications payload, known
both as FAISAT-2v and VITASAT-1R, will be launched aboard
a Russian Cosmos rocket in mid-1996, with service initiation near
the end of the year. If successful, Final Analysis may eventually
launch a constellation of 26 satellites.

From VITA's perspective, the VITASAT communications system contains
several elements (see Figure 1). The first is VITASAT-1R (FAISAT-2v)
that operates in the "little LEO" VHF/UHF bands with
switchable store-and-forward and zero-delay transponder modes.
This satellite will be launched into a 1000 kilometer, 83 degree
inclination orbit and will provide a minimum of four passes per
day for users worldwide (see Table 1 for more satellite specifications).
After a second satellite is launched into a similar orbit, Final
Analysis plans to launch 24 subsequent satellites in four 67 degree
inclination orbital planes of 1000 kilometer altitudes each. All
satellites will provide a minimum access of four passes per day
per satellite to the VITA system for users virtually anywhere
in the world.

Figure 1

The second element is User Terminals (UTs, computers and software)
that are attached to Messaging Terminals (MTs) consisting of packet
radio modems and radio transmitter/receiver hardware, permitting
these stations to send or receive messages from the satellite
as short data packets or large files. Messaging Terminals communicate
with the satellite at either 2400 bps or 9600 bps (in the United
States they are limited to rates of 2400 bps). See Table 2.

In a typical Messaging Service scenario, a UT is connected to
an MT via a local area network over Ethernet or "terrestrially"
via packet radio protocols. The MT receives a message from one
or more UTs and sends this message to the satellite. The satellite
receives the message and routes it to a satellite gateway (currently,
planned for Andenes, Norway, and Capetown, South Africa) where
routing decisions are made to deliver it to a local UT or to send
it through the corresponding Internet gateway. If the destination
is a remote UT, then a return path back through the satellite
gateway to the satellite and to the proper MT will be made.

In addition to MTs, Remote Data Terminals (RTs) will be used for
the transfer of remote telemetry and sensor information for meter
reading and asset tracking. RTs are self-contained units (no computers
attached, unlike the MTs) that transmit and receive short, variable-length
packets via User Ground Stations (UGSs), which are a functional
subset of the Master Ground Station (MGS) and Network Control
Center (NCC) described below. When UGSs and RTs are located within
the same footprint, they can use the zero-delay transponder mode.
This mode precludes the need for store-and-forward re-transmissions
of signals outside the footprint. UGSs communicate with the Data
Service customers using leased lines, public switched networks
(e.g., X.25, frame relay) or the Internet.

The Master Ground Station (MGS) controls the operation of the
satellite constellation, while the Network Control Center (NCC)
handles the data flow and controls all Internet gateways. In addition,
the NCC performs the billing and customer service function, including
technical support. It will be located at Final Analysis offices
in Beltsville, Maryland. Satellite control is performed at the
MGS located at Final Analysis facilities in Logan, Utah. In an
emergency, functions of the MGS and NCC can be interchanged.

As the satellite orbits the earth, it scans the uplink band (149.810-149.9
MHz) at the start of every TDM (time-division multiplexed) frame.
(Over the United States, frame activity begins sweeping in 2.5
kHz steps throughout the uplink band). The frequency of a clear
channel is then identified and broadcast to the MT as the uplink
frequency to be used. Those MTs with messages to uplink then request
time slots within the TDM frame. When the request is acknowledged
by the satellite, the MT uplinks the message in packets of up
to 512 bytes in length (including overhead). This arrangement
permits MT-initiated requests up to a maximum of 7 percent of
uplink capacity. All other uplinks are RT uplinks, commanded by
the satellite through the downlink, since each satellite in the
constellation will maintain location and addressing information
for each MT and RT over which it passes.

E-mail packets are stored in the satellite's mass storage processor
until the satellite passes over a Satellite/Internet gateway station.
As the satellite appears over the horizon, the station will request
and communicate over a dedicated downlink channel, while MT and
RT traffic to the satellite within the footprint of the satellite
continues. The station will then command the mass storage processor
to downlink the messages it has collected at either 19.2 or 38.4
kbps data rate. Next, it will uplink at 19.2 kpbs any messages
to remote users that have arrived at the gateway in time for that
satellite pass. At the end of this sequence, the station will
release control of the dedicated downlink channel, allowing any
other fixed stations (such as UGSs) within the footprint to access
the satellite through this channel. Routing to the Internet from
the gateway then occurs as previously described (see Figure 2).

Figure 2

The Data Service shown in Figure 3 has been designed as a cost-effective
method for commercial and industrial customers in the United States
and elsewhere to gather data from sparsely populated areas. This
service allows users to send small packets of data from RTs used
in applications such as environmental monitoring, asset tracking,
and utility data collection. The Data Service can use UGSs located
in the same footprint as the population of RTs it will serve.
In addition, the Data Service can use the Satellite/Internet gateways
to downlink data collected from areas where there are no UGSs.
While any given UGS will receive a large volume of data, it will
transmit relatively little. All UGSs and RTs in the United States
operate under the same restrictions as the MTs (i.e., packet transmission
spacing of 15 seconds at any given frequency and a burst length
maximum of 450 msec as well as a maximum of 20 transmissions over
a 15-minute interval, all at 2400 bps). Like the Internet gateways,
these hubs are controlled by the NCC. Unlike them, however, the
UGSs have direct links to the commercial and industrial customers
for whom the data are being collected.

Figure 3

The RTs can collect data from a single source or may act as concentrators
for data collected from multiple sources through terrestrial packet
radio or power line transmission systems. In either case, as the
satellite comes into view of an RT population, the satellite begins
the data collection sequence by performing a bandscanning and
frequency assignment sequence in the same manner as the Messaging
Service. Clear channel frequencies will be assigned to the RTs,
which will then adjust themselves accordingly. At this point,
the satellite will transmit interrogation commands to the RTs.
Data from RTs will then be received by the satellite for relay
to a UGS, the NCC, or an Internet gateway.

All RTs and MTs will be given unique addresses under a proprietary
scheme permitting the existence of about four billion separate
units; these addresses are translatable into their IP equivalents.
Each unit will also have a proprietary group address, so that
sites in a common geographical area can be addressed together.
TCP/IP (UDP/IP) packets are encapsulated within proprietary "Final
Analysis packets" for node-to-node transmission. The VITASAT-1R
satellite itself has been assigned a Class C IP host address (198.240.122.200
or faisat.facs.com). The entire system will use all standard TCP/IP
schemes for addressing, routing, and multiplexing different hosts
and networks. In the LEO world, this flexibility can be important
for special applications. For example, small African radio stations
could benefit from IP broadcasting for delivery of "newswire"
information and/or newsgroups to which they otherwise would not
have access, as the cost of standard media news services is prohibitive.
MT design will also be integrated with standard IP-compatible
"ground" protocols, e.g., ethernet, NOS/KA9Q, etc.,
for maximum interchangeability.

Conclusion

From modest beginnings existing prior to the Internet revolution,
VITA has persisted in the quest to bring unserved areas into the
promise of the information revolution through low-cost, radio-based
technologies. Initially overlooked as primitive, low earth orbiting
satellites when combined with the flexibility offered by TCP/IP
protocols over the Internet today offer a rich suite of modern
technological solutions for a wide variety of information requirements.
While essentially store-and-forward, the increasing spectrum of
e-mail-based services available in "real-enough time"
greatly magnify the utility of such low bandwidth systems.

Constraints to deployment of this technology are not now believed
to be technical in nature. Costs should be reasonable, perhaps
as low as $1,000 for mass-produced MTs and USD 50 for 100K of
monthly message transfers, with lower costs in bulk transfers
exceeding this amount. Given many years' experience in training
technicians and engineers from developing countries in radio-based
digital technologies (11), innate abilities to handle advanced
technical material (especially with regard to entrepreneurial
situations) exist and are not viewed by VITA as constraints either.

The real concern is how nations will license and regulate LEO
satellite operations and wireless technologies in general, since
traditional monitoring required when security concerns are paramount
is mostly rendered meaningless. Liberalizing the regulatory apparatus
will probably require a national willingness to analyze distinct
political, economic, legal and cultural milieus with regard to
specific needs addressable by

information-communication technologies. A "cookie-cutter"
approach to this process is generally not possible and must be
developed on a country-by-country basis, and, even better, region-by-region.

VITA continues to hope that the international development community
and national governments will recognize the benefits from net
human capital inflows of knowledge and expertise enhanced by such
communication systems when encouraged without excessive bureaucratic
interference. The ITU will convene the First World Telecommunication
Policy Forum in Geneva in October 1996, which will set forth global
policy principles for global satellite systems, including the
"little LEOs." LEO messaging systems, as one element
in a panoply of wireless communications technologies, can provide
the long-hoped-for technological

"leap-frogging" toward bringing rural areas into the
mainstream of development as the world hurtles toward the 21st
century.

Acknowledgments

The author wishes to acknowledge the substantial contributions
made by Louis Ruffino, Tony Sanders, Rob Atkin, and Mary Kay Williams,
all of Final Analysis, in the preparation of this paper. A special
thanks goes to VITA staff Barbra Bucci who prepared the figures
on short notice and to Henry Norman for his extensive review and
comments.